1. Field of the Invention
The invention relates to a pneumatic structure in the form of a barrel roof which is adapted to be provided over the entirety or a portion of a working or living space, such as a work site for maintaining or painting a watercraft, a construction site, a temporary site for an exhibition, or a stadium, and permits activity even under rain or snow. In particular, the invention relates to a pneumatic structure which is light and is capable of bearing a wind or snow load.
2. Description of the Related Art
Rain or snow often interrupts an outside work which decreases the efficiency of the work. However, there are cases in which the schedule cannot be delayed. Thus, in order to ensure a working or living space such as a work site for maintaining and painting a watercraft, a construction site, a temporary site for an exhibition, or a stadium, and to permit activity even under rain or snow (in the following description, "working or living space" is referred to as "working space"), pneumatic structures in the form of a barrel roof have been developed. Such pneumatic structures include one for semi-permanent use and one for temporary use.
Japanese Unexamined Patent Publication (Kokai) No. 9-144382, which was filed on Jun. 4, 1998 by the applicant, describes a pneumatic structure for temporary use. The pneumatic structure includes outer and inner sheets or membranes connected by reinforcement sheets or membranes in the form of ribs, which define a plurality of air compartments into which compressed air is introduced to inflate the structure. The partition walls include openings which allow air to flow between the air compartments.
The pneumatic structure of the prior art is capable of protecting a working space from rain, but heavy snow and gales, for example winds over 10 m/sec collapse the pneumatic structure. This problem is serious in case of a large structure since the larger the structure, the larger the snow or wind load on the structure.
In addition to the above problems, in order to provide a larger working space, a larger pneumatic structure is required. This increases the weight and the labor for transportation, installation, and deinstallation of the structure.